package com.cjg.useClass;


import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

public class ReadWriteLockDemo {

    public static void main(String[] args) {
        MyCacheLock myCache = new MyCacheLock();

        //写入
        for (int i = 0; i < 5; i++) {
            final int temp = i;
            new Thread(()->{
                myCache.put(temp+"",temp+"");
            },String.valueOf(i)).start();
        }

        //读取
        for (int i = 0; i < 5; i++) {
            final int temp = 1;
            new Thread(()->{
                myCache.get(temp+"");
            },String.valueOf(i)).start();
        }
    }
}

class MyCacheLock{
    private volatile Map<String, Object> map = new HashMap<String,Object>();
    //读写锁
    private ReadWriteLock readWriteLock = new ReentrantReadWriteLock();

    //存，写入的时候，只希望同时只有一个线程写
    public void put(String key, Object value){
        readWriteLock.writeLock().lock();
        try{
            System.out.println(Thread.currentThread().getName()+"写入"+key);
            map.put(key,value);
            System.out.println(map);
            System.out.println(Thread.currentThread().getName()+"写入OK");
        }catch(Exception e){
            e.printStackTrace();
        }finally {
            readWriteLock.writeLock().unlock();
        }
    }

    //取，读，所有人都可以读！
    public void get(String key){
        readWriteLock.readLock().lock();
        try{
            System.out.println(Thread.currentThread().getName()+"读取"+key);
            Object o = map.get(key);
            System.out.println(o);
            System.out.println(Thread.currentThread().getName()+"读取OK");
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            readWriteLock.readLock().unlock();
        }

    }
}